Veterinary session

Deletion of 4 base-pair in the canine ABCB1/MDR1 gene leads to increased drug sensitivity in homozygous mutant individuals of certain herding dog breeds. The mutation has been researched for a long time, numerous scientific reports discuss it. Beside the deletion many other alterations can affect the discussed gene section which are examined also in human medicine. In our study we examine a – in the field of veterinary medicine – lesser-known single nucleotide polymorphism (SNP) in the MDR1 gene, in which a thymine base will be substituted for guanine. Based on its location it is supposed that the SNP may influence the transcellular transport of certain xenobiotics. Our purpose was to examine the presence of the SNP in as many individuals of the selected breeds as possible. The examinations were performed with real-time PCR, restriction fragment length polymorphism and agarose gel electrophoresis. Out of all examined 214 samples we found in 87 cases T/T, in 99 cases T/G and in 28 cases G/G genotype. Out of the four breeds with the biggest sample size we received the following results: 60 German shepherds showed 35 T/T, 23 T/G and 2 G/G genotypes, 34 Shetland sheepdogs showed 2 T/T, 16 T/G and 16 G/G genotypes, 12 Swiss white shepherds showed 3 T/T, 5 T/G and 4 G/G genotypes, and 47 Hungarian vizslas showed 22 T/T, 24 T/G and 1 G/G genotypes. Our results demonstrate that 59% of the tested dogs carried at least one copy of the surveyed G allele. Considering the frequent incidence of the allele and the possibly important role of the SNP in clinical efficiency of some drugs, we urge further clinical studies on the effect of the gene polymorphism, especially on drugs which affect the central nervous system.